To copy a three-dimensional pattern or some other pattern you cannot trace, such as the contours of a wall on which you want to fit a cabinet, first place the new surface at a right angle to the original. Set the point of a compass on the original and the compass’ pencil point on the equivalent part of the new surface.
Draw the compass along both surfaces so that the point of the compass follows the edge of the original, and the pencil point draws its contour onto the new surface.
Another way to copy a three-dimensional pattern is to make a template by pressing a profile gauge against the surface you want to copy. A profile gauge is an assembly of tightly packed needles that draw back when pressed against a surface, taking on its shape.